In daily life, people often enjoy music in leisure time to pacify themselves and lower pressure. People often use a mobile terminal (e.g., a mobile phone, a MP3 player) to play music. As mobile phones are carried around in most time, mobile phones are used mostly and widely. When a user directly uses a mobile phone to play music, others may be disturbed if the music is so loud, especially during a lunch break time at the office or in a room having many people therein. At this point, users may couple an earphone with the mobile phone to listen to music by the earphone, so that others may not be disturbed. For convenience, nowadays many earphones are designed to be wire control type, through which users can directly adjust volume of the music, fast forward the music, or skip to next song, and also can switch on or switch off the play function of the mobile terminal.
Presently, most wire control earphones employ a resistor divider to detect buttons. When a microphone of the wire control earphone is being used in a call, if a button is pressed to adjust volume, bias voltage of the microphone will change, which results in harsh POP noise, thereby affecting quality of the call.